Micro-electromechanical systems (MEMS) are systems which are developed using thin film technology and which include both electrical and micro-mechanical components. MEMS devices are used in a variety of applications such as optical display systems, pressure sensors, flow sensors and charge control actuators. MEMS devices use electrostatic force or energy to move or monitor the movement of micro-mechanical electrodes which can store charge. In one type of MEMS device, to achieve a desired result, a gap distance between the electrodes is controlled by balancing an electrostatic force and a mechanical restoring force. Digital MEMS devices use two gap distances, while analog MEMS devices use multiple gap distances.
MEMS functionality is often degraded or even destroyed by a phenomenon called stiction. Stiction is defined as the strong interfacial adhesion present between contacting crystalline microstructure surfaces. Because the structures of MEMS are so small, forces such as stiction may be stronger than the actuating forces applied to the MEMS and the inherent mechanical restoring forces that would tend to operate the MEMS in a desired manner.
To date, steps taken to ameliorate the problem of stiction have been related to limiting contact between the crystalline microstructure surfaces of MEMS. Attempts to solve the problem of stiction include super critical drying processes, chemical surface treatments and coatings, improved cleaning and etching processes, and the use of structural components adapted to minimize surface area contact. While these steps may reduce the effects of stiction to a degree, none have eliminated stiction as a factor in the operation of MEMS.